Lifting magnet



H. E. HODGSON LIFTING MAGNET March 13, 1951 2 SheetsSheet 1 Filed Jan. 8, 1948 March 13, 1951 H. E. HODGSON 2,545,356

LIFTING MAGNET Filed Jan. 8, 1948 2 Sheets-Sheet 2 Patented Mar. 13, 1951 F'rInG MAGNET Howard E. Hodgson, .Wauwatosa, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wi s., a corporation of Delaware APidication anuar 8, 1948, d i e N 9 1,254

Claims. 1

This invention relates tolifting magnets and is particularly applicable to magnets for lifting and handling material such as sheet or strip steel coils.

It is desirabl in steel mills to lift and han-dle sheet or strip steel coils of various diameters endwise by means of a lifting magnet. "Lifting magnets of various designs have heretofore been provided for this purpose andas heretofore constructed these magnets were provided with a top body member of a diameter at least as large as the outside diameter of the largest coils to be handled by the magnet. Thus when such magnets were placed in lifting position upona coil the entire end surfac of the coil wascovered by the body member so that it was difiicult to see if the magnet was centeredwith respect to the coil to provide for proper lifting thereof. Also it has been found that the diameter of thebody member of such magnets interfered with desired clos stacking of the coils on a storage floor and particularly when the coilswere of fv arious widths and diameters.

The present inven-tion hasamong its ob'ects-to provide an improved coil handling magnet whiph isof such construction as to overcome the aforementioned objections.

Another object is to provide an eifieient-lifting magnet for the aforesaid purpose which is exceedingly simple, r gged and compact in construction and which consists of a relatively-small nurnber of parts which can be readily manufacturedand assembled at low cost.

Another object is to provide an improved-terminal arrangement for lifting magnets 'ofthe aforesaid typeand to also provide improved suspension means'for the bodymember of-the magnet.

Various other objects and advantages of; the invention-will hereinafter appear.

The accompanying drawings illustrate an embodiment -of i the invention which will now be alescribed, ill-being understood that-the embodiment illustrated is susceptibl .of modification without departing from the spirit and scope-of the appended claims.

In the'drawings,

Figure 1 is a topelevationalyiew ofa lifting magnet embodying the invention;

Fig. 2 is a sectional view on line 22 of Fig. 1;

F-ig. 3 is a fragmentary sectional .view on line 3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional view-on line 5-5 o'fFig. 3,-and

"Fig. 5 is adiagrammatic view illustrating various operating features of the magnet structure illustrated inFig. 1.

The lifting magnet illustrated in the drawing is provided with a horizontally disposed body member I of circular form having a pair of primary pole members -2 '.2 and a pair of consequent pole members 3--3 secured to the underside thereof. These parts are formed of material such as cast steel. Each of the primary pole members 2 is surrounded by an energizing winding 4 and each has a cast steel pole shoe '5 securedto the lower end thereof, and each of th consequent pole members -3 has an integral pole shoe 5 formed on the lower end thereof.

-More specifically, the primary pole members 2 and the consequent pole members 3 are arranged alternately and angularly spaced deg. apart about the axis of body m mber 4. The primary pole members-2 are cylindrical in shape and are located midway between the outer edge ofbody member-! and the center axis thereof. The con sequent pole members -'3 are arranged adjacent the outer edge of body member [and are sector shaped in cross section to provid clearance between the-same and the windings 4 on pole members 2. The pole-members 2 ar each secured-to body member I by pair of bolts 8-8 and as shown in Fig. -2-these bolts alsoserve to hold pole shoes 5 in'assembled position upon the lower ends of said pole members. As shown in'Fig. 3, each of the consequent pole members 3 is held in assembled position upon body member i by a pair of bolts -99. Each of the pole members 2 and 3 is accurately positioned and securely held against ---turning and lateral vdisplacement upon body-memberiby-a pair of circular plugs Hll0. These plugs are secured by screws ii withinopenings provided in-the upper ends of pole members 2 and 3 and fit within openings provided in -th under face of body member I. Each-of the pole-shoes 5 is accurately positioned and held against displacementupon its associated pole member-2 by a pair of circular plugs l2 -l2. ,These plugsar secured-byscrews 13 within openings provided in thelower ends .of pole members -2 and fitwithin openings provided in the upper faces of pole shoes .51

The windings 4 associated with .primarypole members :2 "have a, narrow terminal space 15 therebetween andv are made as large aspossible to be included within the boundary of body memher I. rality of insulated coil sections .ifiwhich are formed of strap -copper .wound fiatwise in the fOrmotaspiral. Windings are completely en- .Each of thewindings It comprises a plu closed and held in assembled position upon their associated pole members 2 by a cast metal casing l! which is formed of non-magnetic material such as manganese steel. Casing l i is provided with a bottom wall is and a side wall i9. As shown in Fig. 2, bottom wall is is provided with openings for receiving the lower nds of pole members 2 and as shown in dotted lines in Fig. 1 side wall is is shaped to closely surround the windings ii and to provide a contracted neck portion 29 therebetween. Pole shoes 5 abut the bottom wall it of casing ii to hold said casing in assembled position upon the under face of body member I. g

As shown in Figs. 1 and 3-, one side of the neck portion of casing H is provided with spaced openings for receivin a pair of insulated binding posts 2l--2l. The inner ends of these binding posts are connected to windings :5 by suitable leads located within the terminal space l5 and the outer ends thereof are connected to a pair of insulated terminal leads 22 which extend upwardly through an opening provided in body member i. As shown in Figs. 3 and 4, the consequent pole member 3 adjacent binding posts 2! has a pair of sheet metal shields 23-23 fixed thereto for enclosing and protecting the outer ends of said binding posts. For a purpose hereinafter set forth, windings i are electrically connected to render the primary pole members 2 and their associated shoes '5 of like polarity.

The pole shoes 5 on primary pole members 2 and the integral pole shoes 6 of consequent pole members 3 are radially disposed with respect to body member i and project outwardly beyond the periphery thereof. As shown in Fig. 1, pole shoes 5 and 6 are of relatively large area and of ovate shape in a horizontal plane, and as shown in Figs. 2 and 3 the outer ends of said shoes are tapered and of reduced thickness. The under faces of pole shoes 5 and 6 are formed to provide similarly shaped elongated pole faces 25 which are radially disposed with respect to body member I. As shown in dotted lines in Fig. l, the inner ends of pole faces 25 are elongated and of narrow width and the outer ends thereof are flared outwardly and of increased width.

As is apparent, when the aforedescribed lifting magnet is placed in lifting position upon the end of a coil of larger diameter than body member I the outer edge of the coil is exposed between the projecting ends of pole shoes 5 and 6 So that it is possible to see when the magnet isplaced in centered position upon the coil to provide for proper lifting thereof. Body member l of the magnet may be made of a standard diameter to handle coils of strip or sheet steel of various diameters within a selected range. For example, if the coils which are to be handled by the magnet are of various sizes exceeding 50 inches in diameter, bod member 5 may have a standard diameter of 46 inches. Pole shoes 5 and 6 are then designed to extend radially across ali convolutions of the largest strip steel coils which are to be handled by the magnet. Thus if strip steel coils up to 60 inches in diameter are to be handled by the magnet, pole shoes 5 and ii are made sumciently long to extend slightly beyond the periphery of, such coils when the magnet is placed in centered position thereon. v

As hereinbefore stated, windings i are electrically connected to render primar pole members 2 and their associated shoes 5 of like polarity. Assuming that pole shoes 5 are of positive polarity, the consequent pole shoes 5 will then be of 4 negative polarity. Thus when the magnet is placed in centered position upon the end of a coil, the flux generated by windings 4 will pass in opposite directions from primary pole shoes 5 along the convolutions of the coil to consequent pole shoes 6, as indicated by arrows in Fig. 5. In practice it has been found that this flux distribution renders the magnet exceedingly efficient in that substantially the entire flux generated by windings 4 passes through the coil con volutions in a direction substantially parallel thereto. Also it has been found that when pole shoes 5 and 6 are shaped as hereinbefore de scribed the outer convolutions of a strip steel coil are subjected to greater attractive force than the inner convolutions thereof, as is required for proper lifting of the coil. The above described magnet construction is also advantageous in that the pole arrangement thereof permits coils of various widths and diameters to be placed closely together on a storage floor in parallel rows A--A and BB, as shown in Fig. 5.

The above described magnet is supported in the usual manner by three radially disposed chains which are connected to a common hoisting cable concentric to the axis of body member I and body member I has three suspension lugs 2! formed on the upper side thereof for attachment to these chains. The lugs 2? are of narrow width and are radially disposed in equally spaced angular relation about the axis of body member i. As shown in Fig. 1, one of the lugs 27 is aligned with the axis of the left hand primary pole member 2 and the securing bolts 8 associated with said pole member are arranged on opposite sides of said lug. Each of the lugs 2'! is provided with a transverse chain receiving slot 29 and each of the same is also provided with a longitudinal opening for receiving a chain securin pin 36. As shown in Fig. 2, each of the pins 30 is held in assembled position upon its associated lug 2? by a washer 3!. Each of the washers 31 is secured to the outer end of its associated lugs 27 by a screw 32 and engages within a recess 33 formed in the outer end of its associated pin 36. i

What I claim as new and desire to secure by Letters Patent is:

1. A coil handling magnet which comprises a circular magnet frame, a plurality of positive poles and a plurality of negative poles depending from the underside of said frame in alternate and spaced relation symmetrically about the central axis of said frame, said positive poles having energizin windings and said negative poles being unwound, and all of said poles having at their lower ends a pole shoe projecting radially of the central axis of said frame and extending a substantial distance beyond the peripher thereof, thereby affordin clearance therebetween for visibility from above of substantial sectors of the top of the coil lying beyond the periphery of said frame when being handled by the magnet.

2. In an electromagnet for endwise lifting of strip metal coils, in combination, a circular magnet frame, a plurality of wound positive poles and a plurality of unwound negative poles depending from the underside of said frame in alternate and spaced relation symmetrically about the central axis of said frame, each of said poles having at its lower end a pole shoe which projects radially of the axis of said frame a substantial distance beyond the periphery thereof, said pole shoes having clearance therebetween for visibility from above of substantial sectors of the top of the coil lying beyond the periphery of said frame thereby affording substantial tolerance in concentricity of said coil with said frame when lifting said coil.

3. A coil handling magnet which comprises a circular magnet frame, a plurality of positive poles and a plurality of negative poles depending from the underside of said frame in alternate and spaced relation symmetrically about the central axis of said frame and each having a pole shoe which projects a substantial distance beyond the periphery of said frame, said positive poles having energizing windings and said negative poles being unwound, and a single casing surrounding all of said windings and forming with said frame a complete enclosure therefor leaving said unwound negative poles unenclosed, and simultaneously forming an enclosed terminal space between said windings.

4. In an electromagnet for endwise lifting of strip metal coils, the combination with a magnet frame having depending from the underside thereof a pair of primary pole projections and a pair of consequent pole projections in alternate and spaced relation, an energizing winding for each of said primary pole projections, said consequent pole projections being unwound, a casing surrounding said primary pole projections and their windings forming with said frame a complete enclosure therefor leaving said unwound consequent pole projections unenclosed, and a pole shoe mounted on each of said primary and consequent pole projections, which pole shoes extend a substantial distance beyond the periphery of said frame and have substantial clearance therebetween for visibility from above of substantial sectors of the coil lying beyond the periphery of said frame.

5. In an electromagnet for endwise lifting of strip metal coils, in combination, a circular magnet frame, a plurality of positive poles and a plurality of negative poles depending from the underside of said frame in alternate and spaced relation symmetrically about the central axis of said frame and each having a pole shoe which projects a substantial distance beyond the periphery of said frame, said positive poles having energizing windings and said negative poles being unwound, a single casing surrounding all of said windings and forming with said frame a. complete enclosure therefor leaving said unwound negative poles unenclosed and simultaneously forming an enclosed terminal space between said windings, a pair of insulated terminal elements extending outwardly through openings in said enclosing casing, and a pair of insulated terminal leads connected to the outer ends of said terminal elements and extending upwardly through an opening in said frame.

HOWARD E. HODGSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 687,931 Barr Dec. 3, 1901 1,094,106 White Apr. 21, 1914 1,416,860 Nelesen May 23, 1922 1,484,090 Simmons Feb. 19, 1924 1,489,284 Steininger Apr. 8, 1924 2,220,561 Ward Nov. 5, 1940 

